Xylem H-3521 - Manual (Page 13)

H-3521
Installation 2-3
Figure 5 Pressure & Vent Ports
2.5 Making Connections to the Pressure Port
The H-3521 has a 1/8" female NPT pressure port for making connections to your pressure source.
Apply Teflon tape or anaerobic thread dope to help prevent leaks. The pressure port has a
stainless steel plate to prevent the port fitting from spinning in the housing. Make certain the
“keeper” plate is in proper position. Whenever possible, use a backup wrench to avoid damaging
the enclosure. Before tightening the pressure port connection, bleed any air from the supply line.
Trapped air in the supply line will slowly dissolve into the water, as it does the density of the
water column changes from air to water and the pressure offset will drift.